A sustainer for electric stringed musical instruments is sometimes considered to be a subclass of other electronic devices which modify the electric pickup signal of the instrument in order to enhance the sound which is heard from the instrument amplifier. These devices have been referred to as "electronic sound effect devices", otherwise simply called "effectors" or "effects" for musical instruments. They are widely used accessories for the creation of music with electric guitar. When examined more closely, however, a fundamental difference exists between sustainers and other effectors for stringed musical instruments: Other effector devices specifically modify the electrical signal produced by the instrument pickup. Then, this modified pickup signal is sent to the instrument amplifier. What the listener hears is this modified pickup signal. Conversely, sustainers split the pickup signal into two branches. One branch is sent to the instrument amplifier or other effects without any alteration other than standard volume and tone controls, which are basic functions of electric guitars. The other branch is sent to the sustainer, where the pickup signal is amplified and processed. Then, the amplified, processed signal is not sent to the instrument amplifier, but instead is sent to the string driver transducer. The transducer then converts the amplified electrical energy into vibrational energy which is imparted to the strings. This difference is important, and will be referred to frequently in the description which follows. Furthermore, the sustainer transducer must be attached to the instrument, or must be held in close proximity to the instrument strings in order for the sustainer to function properly.
These differences between sustainers and other effectors are crucial to the development of the present invention. They will be referred to frequently in the description which follows. First, however, it will be helpful to review effectors in general.
Electronic effectors for electric guitar have been available for about fifty years, ever since the invention of the electric guitar. Among the first electronic guitar effectors available were reverberation and tremolo devices. These early devices were sometimes included inside certain models of guitar amplifiers. Control of an early effector typically consisted of one or two potentiometers which were mounted onto the control panel of the amplifier, which were actuated by control knobs. Also, often one or more foot-actuated switches were mounted inside of a metal housing which was designed to sit on the floor, for convenient access by the musician in turning the effect on and off. The metal housing has come to be called a "floorbox", or the slang expression "stompbox". Eventually, with the advent of the transistor and other electronic miniature components, the entire effector evolved to be housed in floorboxes as accessories which sat on the floor, separate from the guitar amplifier. Additionally, several effector devices have been installed inside of production electric guitars, and also as retrofit items into existing instruments. Various switches and knobs have been used to control these in-guitar effectors, and are typically mounted onto the body of the instrument within easy reach of the musician.
At the present time, effector sales for electric guitar in the U.S. alone is approximately $86 million, with over 650,000 units being sold annually. These figures are according to the 1998 sales data published by NAMM, the National Association of Music Merchants. The data include only floorbox units having one or more effects contained within. Many different electronic effectors are currently available. The 1998 Guitar and Bass Buyer's Guide, published annually by Miller Freeman Publishing Company, San Francisco, Calif., lists seventy-one different manufacturers of electronic effectors for electric and acoustic guitar, and lists 470 different effector models. All of the effectors listed in that publication are similar in that they have one thing in common: They are inserted into the signal path of the guitar pickup signal. There, they change the tone or distortion characteristics of the pickup signal, or add time-delay effects such as echo and reverberation to the signal.
A fundamental requirement for the design and placement of the controls of effectors is that they be easily accessible to the musician, so as to enhance the creation of music. Turning the effector on and off during performance should not interfere with the musician in such a way as to impede playing movement of the hands. If the controls are hand-actuated, they must be placed near the playing position on the instrument so as to minimize actuation effort.
By far, most of the effector devices currently available are housed in floorboxes. These utilize foot-actuated switch controls to actuate the on/off switch for the effector. Sometimes they contain a foot-actuated potentiometer in order to modify a certain parameter, such as tone or modulation of a time delay. With modern-day miniaturization of electronic circuits, effector floorboxes can be made quite small. It has become standard practice for musicians to use several effector boxes simultaneously, connecting them in series in the signal path. Alternately, numerous "multi-effectors" exist which combine several electronic effector circuits into the one housing, having more than one foot-actuated control.
FIG. 1a shows, in perspective view, a typical popular effector with foot-actuated switch control. The effector, 100, is manufactured by ProCo Sound, of Kalamazoo, Mich. It is called "The Rat". Its function is to apply very high voltage gain to the pickup signal in order to overdrive an internal amplifier, thereby producing a large amount of distortion in the sound. Foot-actuated double-pole, double-throw switch 101 turns the effector on and off. FIG. 1b shows a schematic block diagram of certain parts of the effector circuit. Block 170 represents the actual internal circuit details of the effector, which are not shown.
A pickup output signal is applied to input connector 110, which is a common 1/4 inch stereo phone jack, through plug 150, which is a common 1/4 inch phone plug. The input signal enters the effector through the tip connection 154d of the plug, and connects to tip connection 114 of the jack. The input signal is applied to common terminal 106 of switch pole 101a. In the "on" position of switch 101, the incoming signal is applied to input terminal 174 of circuit 170 through terminal 107. The output signal of the effector passes from output terminal 176 of circuit 170 to tip terminal 122 of output jack 120. In the "off" position, the pickup signal bypasses the effect through signal path 180. When the effector is off, the input signal is applied directly to tip terminal 122 via signal path 180. Knob 102 is labeled "DISTORTION", and adjusts the amount of voltage gain of the internal circuit by varying the setting of an internal potentiometer 102a. Knob 103 is labeled "FILTER", and adjusts equalization via a variable filter which is varied by potentiometer 103a. The third knob 104, labeled "VOLUME", adjusts the effector output volume level via an internal potentiometer 104a. Typically, once the potentiometer settings are established, they are only occasionally reset at convenient intervals during performance.
Battery 160 is the power supply for the effector. Positive terminal 162 of battery 160 is connected to terminal 171 of effector circuit 170. Negative battery terminal 164 connects to ring terminal 114 of jack 110. The power supply circuit is completed when a standard monaural 1/4 inch phone plug 150 is inserted into input jack 110. The shield terminal 152 of plug 150 connects to ring terminal of jack 110, shorting it to ground through shield terminal 118 of jack 110. This completes the electrical circuit and applies ground to terminal of 178 of circuit 170.
Many effectors have been designed to fit inside of electric guitars. This type of effector became popular for a time during the 1970's, when analog and digital electronic integrated circuit technology started to become a major industry. Then, for the first time, it became possible to design and to economically manufacture miniature electronic circuits of high complexity. Electronic effects could then be fit into an electric guitar of normal size, with minimal power consumption.
One example of "in-guitar" effectors is the "Electra" electric guitar, distributed during the 1970's by Saint Louis Music Company. This guitar featured two "MPC" (modular powered component) modules which were installed inside the instrument, which could be selected from a variety of available modules. Dedicated knobs and toggle switches, which were mounted to the top of the guitar body, were used to control the effector modules. The modules plugged into a custom connector inside the instrument.
The use of internal MPC effectors for the Electra guitar quickly peaked and has lost popularity. This could be because of the difficulty with keeping abreast of rapidly evolving technology of the effector product. Only a limited number of "MPC" modules were available, and only MPC modules fit into the custom connector of the Electra guitar. As a result, effector choices were limited. Most musicians preferred the flexibility of being able to choose from a wide variety of floorbox effectors, constantly evolving as technology progressed. Another factor which probably contributed to the mediocre success of in-guitar effectors is because the inclusion of in-guitar effectors necessitates the addition of switches and potentiometers on the front of the instrument body. This tends to clutter its appearance. The most popular electric guitars are those which have only a fundamental set of controls for volume and tone, plus a pickup selector switch. The "in-guitar" effector is still available, but is not nearly as popular as floorbox effectors. Most of the in-guitar effectors which are currently sold as retrofit items are enhancements of basic tone and volume control functions, as opposed to the more esoteric effectors which are available. None of the effectors listed in the 1998/1999 Guitar/Bass Player's Guide is an "in-guitar" effector.
Most electric guitars which have been manufactured since the invention of the electric guitar have basic function controls built into the body of the instrument. These are generally regarded as being basic to the operation of the instrument, and as such are not generally regarded as effectors. An inspection of the 1998 electric guitar catalogs of Fender Musical Instruments and Gibson Guitars, two world leaders in electric guitar sales, reveals that all of their listed models have only the following controls mounted to the body instruments: Volume controls, tone controls, and pickup selector switches. These are the controls which have become generally regarded as standard in the industry. Departures from this have not gained mass popularity. The volume controls are usually given "priority position" over the tone controls, as is evidenced by the fact that on most electric guitars a volume control is placed nearest the string-playing position. The pickup selector switch, which is used to select a particular pickup or combination of pickups in order to achieve the desired sound, is placed at a convenient position on the body of the instrument. These switches take numerous forms. Commonly used switch types are toggle, slide, and rotary multiple-position selector switches. The pickup selector switch has also withstood the test of time, and is present in nearly every electric guitar which has multiple pickups.
FIG. 2a shows in front plan view a popular electric guitar, 200, the well-known "Stratocaster.RTM.", manufactured by Fender Musical Instruments, Scottsdale, Ariz. Bridge pickup 210 is shown near bridge 205. Neck pickup 212 is shown adjacent to neck 215. Middle pickup 211 is shown between bridge and neck pickups. All controls, pickups, and neck are mounted to body 201. Pickup selector switch S270 is a lever-actuated, rotary-type switch, having five detent or "stop" positions. It is used to select one particular pickup or a combination of pickups, depending upon the detent setting of the switch. Volume control knob 220 is shown closest to the strings 240-245 on pickguard 202 for convenient access. Tone control knob 221 controls the tone of middle pickup 211. Tone control knob 223 controls the tone of neck pickup 212.
FIG. 2b shows an electrical schematic of a common version of the Fender "Stratocaster.RTM." guitar. Pickups 210, 211 and 212 are depicted schematically as coils. One end of each coil is connected to common, or "ground" terminal 280. The other ends of the three coils are connected to terminals 271a, 271b, and 271c, respectively, of first pole 271 of five-position rotary pickup selector switch S270. Pole 271 is rigidly mechanically connected and also electrically connected to second pole 272 of switch S270. The electrical junction of the two poles is connected to guitar output terminal 231 of output jack 230 through volume control potentiometer 220a.
Pole 271 is rotated by applying finger pressure on handle 274 of pole 271. Since pole 272 is rigidly mechanically connected to pole 271, pole 272 rotates as pole 271 rotates. Detents 275a-275e are present on detent plate 275. These detents allow tip 276 of pole 272 of rotary pickup selector switch S270 to stop in five discrete positions.
Conductor 277 of pole 271 is depicted as connecting only to contact 271 a in detent position 275a in FIG. 2b. Contact 271a therefore connects only the bridge pickup 210 to volume potentiometer terminal 224. In this detent position 275a, pole 272 connects only to switch terminal 272a, which is not connected to anything. In detent position 275b, conductor 277 of pole 271 connects to both contacts 271a and 271b, bridge pickup 210 and middle pickup 211. This connects both bridge pickup 210 and middle pickup 211 to the output. Also in detent position 275b, conductor 278 of pole 272 connects to both switch terminals 272a and 272b. This connects pole 272 to potentiometer 221a, which is in turn connected to one end of capacitor 219 through potentiometer wiper terminal 221b. The other end of capacitor 219 is connected to ground. The combination of potentiometer 221a and capacitor 219 constitutes a tone control for middle pickup 211, by attenuating high frequencies when wiper terminal 221b is rotated toward terminal 221c, which corresponds to maximum counterclockwise rotation of knob 221.
In detent position 275c, conductor 277 of pole 271 selects only middle pickup 211 via switch terminal 271b. Also, conductor 278 of pole 272 selects tone control capacitor 219 and potentiometer 221a. In detent position 275d, which is depicted in FIG. 2b by showing pole 271 as dashed line 274a, and by showing pole 272 as dashed line 276a, connector 277 of pole 271 selects switch terminals 271b and 271c, which are connected respectively to pickups 211 and 212. Also, conductor 278 of pole 272 selects middle pickup tone control consisting of capacitor 219 and potentiometer 221a, and neck pickup tone control consisting of capacitor 219 and potentiometer 222a. In detent position 275e, conductor 277 of pole 271 selects only neck pickup 212 via switch terminal 271c. Also, pole 272 selects neck pickup tone control consisting of capacitor 219 and potentiometer 221a.
One problem with the configuration just described is that it is not possible to select the combination of bridge and neck pickups and still have the other pickup combinations with the selector switch S270 as shown. This extra pickup combination is sometimes desired by musicians.
In order to correct this shortcoming, another type of switch is often installed into electric guitars as a aftermarket item. This is a common "pull-on/push-off" switch which is built into a rotary-shaft potentiometer. By pulling the potentiometer shaft, the switch is actuated. FIG. 3a shows in rear/side perspective view a potentiometer/switch combination 300. Potentiometer VR305 is shown with double-pole/double-throw (DPDT) switch 310 attached. This type of switch is actuated by pulling and pushing on potentiometer shaft 302. When shaft 302 is pulled, shown by arrow 340 of FIGS. 3a and 3b, terminals 330 and 331 slide in the direction of arrow 340 and short switch terminals 312 to 313 and 315 to 316, respectively. When shaft 302 is pushed, shown by arrow 341 of FIGS. 3a and 3c, terminals 330 and 331 slide in the direction of arrow 341 and short switch terminals 312 to 311 and 315 to 314, respectively. Alternatively, potentiometer/switch combinations are available with push-on/push-off (push-push) function, or with momentary push-on or push-off. For switches with the push-push or momentary function, direction arrow 340 of FIG. 3 has no meaning. These various types of switch/potentiometer combinations are popular because they do not change the visual appearance of the surface of the instrument body. This is because only the potentiometer control knob is visible to the observer. Furthermore, the potentiometer/switch combination can often be added into a standard electric guitar electronics cavity without the necessity of enlarging or modifying the cavity.
The electrical schematic of FIG. 2c shows one of these potentiometer/switch combinations. In this schematic, a pull-on, push-off switch/potentiometer combination 300 is used to replace neck pickup tone potentiometer 222a of FIG. 2c. With this option, neck pickup 212 can be selected in combination with bridge pickup 210, when rotary selector switch S270 is in detent position 275e by pulling on potentiometer shaft 302, which actuates switch 310. Alternatively, all three pickups can be selected when rotary selector switch S270 is in detent position 275e by pulling on potentiometer shaft 302.
FIG. 2d shows another switching option of FIG. 2c, wherein a momentary push-off switch/potentiometer combination 290 replaces tone control potentiometer 221a of FIG. 2b. Switch 292 is connected in series with the output jack. Switch 290 is a momentary-action switch, whereby the switch is actuated by pushing the potentiometer shaft. The pushing direction is indicated by arrow 294. When pushing is ceased, the switch automatically returns to the rest position by a spring (not shown). This particular scheme allows an instant "cut-out" feature, where the output signal of the electric guitar is silenced whenever the tone control knob of the middle pickup is pushed. This type of arrangement is sometimes used by musicians to produce a "staccato" type of effect.
Alternative configurations of potentiometer/switch combinations are available, such as potentiometers having two concentric shafts, where one shaft controls the potentiometer setting and the other controls a rotary switch, as shown in rear/side perspective view of FIG. 3d. This drawing shows the potentiometer/switch combination of FIGS. 3a, 3b, and 3c, but having additional shaft 302a shown inside shaft 302, which is hollowed out to accept shaft 302a in concentric fit. With this potentiometer/switch combination, actuation of switch S310 can be pull-push, push-push or push momentary. Also, rotary would be possible. This type of switch/potentiometer combination is typically used with two concentric or stacked actuation knobs (not shown), which are attached to each shaft to make actuation more convenient. Most often, inner shaft 302a is used to actuate switch S310 and outer shaft 302 is used to actuate potentiometer VR305. On some switch/potentiometer combination units, outer shaft actuates rotary switch S310.
Other functions are often added to electric guitars on a custom basis, using these switch/potentiometer combinations. Sometimes they are used to select a winding tap on a pickup for additional pickup sounds, or to bypass a volume control in order to quickly change between predetermined backup and solo playing levels. Many other functions are possible. Potentiometer/switch combinations are an especially popular retrofit accessory to customize a guitar's basic control function. The main reason for this popularity is because this type of switch can often be installed on an instrument without having to modify the body or change the physical appearance of the instrument. Since the switch is an integral part of the potentiometer, no new hole has to be placed in the instrument body or pickguard to accommodate the switch. This is a very important advantage of this type of switch, which is becoming more important as time passes. One primary reason for this importance is because the antique value of older electric guitars is increasing, due to the fact that the electric guitar was invented over fifty years ago. Older guitars are worth more on the collector market if they have not been altered in appearance by cutting holes in the body to accommodate electronic modifications. Because of this type of switch/potentiometer combination, a particularly valuable instrument can be modified temporarily with the addition of an onboard effector control, and then returned to its original condition with little or no change to the antique value of the instrument.
Books and magazines are available which describe many retrofit modifications using potentiometers and switches. Guitar Player Magazine, published by Miller Freeman of San Francisco, Calif. is a magazine which often has articles on guitar modifications using potentiometers and switches. The Stewart McDonald Guitar Shop Supply catalog, published several times per year by Stewart McDonald Guitar Shop of Athens, Ohio, sells such switches and potentiometers, and also contains numerous articles on clever retrofit ideas. Another catalog containing guitar electronic parts is WD Music Products, of Ft. Meyers, Fla. A book called Guitar Electronics for Musicians, by Donald Brosnac, published by Wise Publications of London, England, describes many standard and custom electronic control plans and embellishments for electric guitar. Numerous other books are available on the subject.
Sustainer Prior Art
Sustainers for stringed musical instruments have been described as early as 1892 in U.S. Pat. No. 472,019 to Ohmart. This is the earliest description of such a device known to this inventor. Some 35 patents exist on sustainers for musical instruments. However, as far as this inventor knows, no prior art sustainer for musical instruments has achieved any significant commercial success until the late 1970's. This could be due partly to a combination of two factors: (a) The onset of miniaturized integrated silicon chip electronics which started to mature in the early 1970's has probably favorably affected the progress of sustainers as it has other effector types; (b) The development of certain "rock", "jazz", and "country" music playing styles for electric guitar during the last thirty years which involves producing sustained string vibration of electric guitar, whereby the musician stands in close proximity to a loud guitar amplifier, and takes advantage of sympathetic vibrations induced into the guitar strings as the intense acoustic vibrations of the amplifier loudspeaker impinges upon the guitar strings, has undoubtedly generated interest in sustainers.
The earliest sustainer known to this inventor to have achieved any degree of commercial success is the "E-Bow", or "Energy-Bow", manufactured by Heet Sound of Los Angeles, Calif. This sustainer is described in U.S. Pat. No. 4,075,921 to Heet, Feb. 28, 1978. It will be described later on in context with explanations of other sustainer types. Since then, other types of sustainer devices have appeared on the market with some commercial success. Most of those sold are used for electric guitar, but they are not limited to that application. Several embellishments and versions of sustainers are known to exist or have been publicly disclosed as patents.
Examination of retail store displays, public guitar shows and conventions around the U.S., and advertisements in guitar magazines reveals that while there has been some acceptance of the sustainer in the marketplace, sales of sustainers to date have not been as commercially successful as for other musical instrument effectors.
One reason for heretofore lackluster market penetration and general acceptance is that many musicians consider the sustainer to be an esoteric effect. This inventor believes that another reason concerns the enclosures in which prior art sustainers have been housed and the manner in which the controls of the sustainers are placed for use by the musician. In order to understand this reasoning, it will be helpful to understand musical instrument sustainers more completely, and to understand the distinct differences between sustainers and signal-processing effectors.
Sustainer Elements
FIG. 4 shows, in block diagram form, a sustainer for a stringed musical instrument. A stringed musical instrument having a sustainer must have one or more electric pickups 410, in order to convert some of the vibration energy of the instrument string or strings 430 into pulsating, or alternating electrical energy, at the pickup output 412 in response to the string vibrations, where electrical energy is defined as the product of voltage and current.
A sustainer 400 for stringed musical instruments comprises at least the following four elements:
(1) A control system 440, which comprises of one or more of the following control functions (not shown in FIG. 4): (a) one or more on/off switches; (b) one or more phase reversal switches for harmonic string vibration control; (c) potentiometer to control drive signal amplitude to the driver transducer; (e) potentiometer to control equalization; (f) potentiometer to control phase shift of the pickup or transducer signal; PA1 (2) An amplifier 450, to amplify the alternating electrical energy from the pickup output; PA1 (3) A power supply 460, usually either a dc battery or an ac line-powered supply, which is used to power the controller/amplifier; PA1 (4) A driver transducer 420 which converts the amplified alternating electrical energy from the driver amplifier output into either alternating magnetic energy or pulsating acoustic energy, which is then coupled to the strings to replenish vibration energy to the strings which is normally lost due to friction.
A sustainer for stringed musical instruments is different from other effectors in two significant aspects:
(a) All other effectors modify the tone instrument output signal in some way. The sound which the listener hears from the instrument amplifier is this modified instrument output signal. A sustainer does not do operate on the instrument output signal. Instead, its basic function is to first split up the pickup signal into two branches. One branch is passed on to the instrument amplifier or other effectors as the instrument output signal, where it is heard without any further processing by the sustainer. The other branch is passed on to the sustainer controller and amplifier. The sustainer then operates on the instrument strings, not on the instrument output signal.
(b) For all sustainers known to this inventor, the string driver transducer must be either physically attached directly to the instrument or placed within about 1/4 inch from a string being sustained. This is a necessary condition to impart vibrational energy into the strings.
These two aspects have had a significant impact on the mechanical characteristics of the housing of recent commercially-available sustainers, and also on how the controls of the sustainers have been arranged. For some sustainer types, the most practical housing is the instrument body itself. For another type, only the transducer is attached to the instrument body, with the rest of the sustainer components being housed inside of a floorbox. For still another type of sustainer, all components are housed inside of a small, hand-held box, which is brought near a string when the sustain function is desired.
Several different controls can be found on sustainers. All sustainers known to this inventor have at least a switch for turning the sustainer on and off. If this switch is readily accessible, then the musician can easily and quickly turn the sustainer on and off. This can be either by foot-actuated switch in the case of sustainers which have their control and amplifier circuits housed inside of a floorbox, or on the body of the instrument in a convenient position. Other arrangements are possible. Another useful control found on most recent commercial sustainers is the phase reversal switch of the transducer signal, for harmonic vibration control. This control should also be easily accessible to the musician. Still another useful control is to have a potentiometer which controls the amplitude of drive signal which is applied by the amplifier to the transducer. Therefore, it is preferable that the control of such a potentiometer for the sustainer consist of footpedal-actuated potentiometer, or a potentiometer which is mounted onto the instrument body near the string-playing position. Another useful control is one or more frequency control potentiometers, in order to change the frequency response of the drive signal, which alters the harmonic content of the drive signal, and consequently changes the harmonic vibration mode of the strings. Another way to accomplish changing of the string vibration harmonic mode is to provide a phase alteration control of the drive signal via a potentiometer.
Sustainers exist such that all of their basic elements are permanently attached to or contained inside the body of an instrument. Others exist such that only some of the basic elements are attached to or contained inside the instrument, and such that none of the basic elements are attached to or contained inside the instrument.
Sustainer Types
Most existing sustainers for stringed musical instruments can be classified into two main types: (A) Electromagnetic sustainers; (B) Electroacoustic sustainers. For both types of sustainers there are no significant differences between elements (1)-(3) as described above. The main difference between them is the type of driver transducer (4) being utilized.
String driver transducers for both electromagnetic sustainers and electroacoustic sustainers can be similar in operation, in that both are typically electromagnetic devices. Both types of transducer typically incorporate one or more coils, each coil being wound around a corresponding magnetic core. For both types of transducer, an alternating amplified electrical voltage is applied to each coil from the amplifier output. An alternating electrical current in the coil results from the applied alternating voltage. This alternating electrical current then produces a corresponding alternating polarity or pulsating-amplitude-same-polarity magnetic field in the respective core, depending on whether or not the core is biased with a permanent magnetic field.
The difference between the two types of sustainers lies in the manner in which the alternating or pulsating magnetic field in the core is used. For the magnetic sustainer, a pulsating-amplitude-same-polarity magnetic field is produced in the core and extends away from the core, impinging directly upon the instrument strings. This adds vibrational energy to the strings during each vibrational cycle. For the acoustic sustainer, the alternating polarity magnetic field produced in the core impinges upon one or more permanent magnets, causing the magnets to vibrate mechanically, in phase with the alternating polarity magnetic field produced in the transducer core. The permanent magnets are rigidly attached to a part of the instrument, but are held apart from the transducer core or cores by some flexible spacer, such as a piece of resilient foam rubber, so that the magnets can move relative to the cores. The acoustic vibrational energy of the permanent magnets is transmitted through the instrument body to the strings or directly to one of the ends of the strings, causing their vibration to be sustained.
(A) Descriptions of Electromagnetic Sustainers Follow
(A-1) Coil/Core Magnetic Driver
Electromagnetic sustainers of this type utilize a driver transducer which produces pulsating magnetic energy in response to the drive signal from the amplifier. The pulsating magnetic energy then impinges upon the vibrating strings at a location remote from the ends, to replenish their vibration energy, which is normally lost due to friction. This type of driver transducer only works for strings which are made of magnetic steel.
The transducer is built with one or more coils wound around corresponding magnetic cores. A permanent magnet is attached directly to each core. This produces a magnetic flux in each core, of polarity depending on which face of the permanent magnet contacts the core. The magnetic flux attracts the string or strings of the instrument. Then, as the alternating electrical voltage from the amplifier is applied to each coil, an alternating electrical current flows in the coil. The alternating electrical current in each coil produces a corresponding alternating magnetic field in the core, which adds or subtracts, depending on the instantaneous polarity of each magnetic pulsation, from the permanent magnet field existing in each core due to the permanent magnet attached to each core. This produces a pulsating attraction of one magnetic polarity on the vibrating strings in response to the amplifier signal, which tends to increase the vibrational energy already contained in the strings. One coil/core driver can be used to sustain vibration of a single string or of multiple strings, just as a pickup coil/core can be used to sense vibrations of one or more strings.
Several examples and patents of sustainers utilizing reverse pickup drivers exist. Very little information is contained in the patent information regarding specific control schemes, except that in some cases, switches and potentiometers are described or claimed as being present.
U.S. Pat. No. 472,019 to Omhart describes no embellishment or arrangement of controls adapted to any particular instrument in order to enhance the user's ability to use the sustainer or to enhance the appearance of the instrument. U.S. Pat. No. 1,002,036 to Clement describes a switch, but no particular embellishment or arrangement of controls adapted to any particular instrument in order to enhance the user's ability to use the sustainer or to enhance the appearance of the instrument. U.S. Pat. No. 2,600,870 to Hathaway et al, describes a sustainer and also a reverberation device which uses a single magnetic driver that drives all of the strings of an electric guitar. However, no switching or controls is described. U.S. Pat. No. 3,185,755 to Williams et al., May 25, 1965, also describes a sustainer having a driver which magnetically drives several strings, and furthermore describes a switch. However, '755 describes no special embellishment or arrangement of controls adapted to any particular instrument in order to enhance the user's ability to use the sustainer or to enhance the appearance of the instrument. Moreover, the Williams sustainer describes inducing sympathetic vibration of strings in response to notes played on another instrument, not self-sustaining notes played on the strings.
U.S. Pat. No. 3,742,113 to Cohen, Jun. 26, 1973, describes a magnetic transducer which applies a pulsating magnetic field to a string. Also described and claimed are switches to control the sustainer. However, the Cohen patent shows the arrangement of switches mounted onto the surface of the instrument in a convenient position in order to enhance the user's ability to use the sustainer. The switches are numerous and are visible to the casual observer. The problem with this type of control system is that toggle switches are mounted to the body of the instrument, which clutters the appearance. If the sustainer is used as a retrofit item, then the end user would have to modify the body of the instrument in order to mount the switches. This would likely decrease the value of the instrument.
U.S. Pat. No. 4,243,575 to Oliver, Mar. 13, 1979, describes a sustainer having a high frequency amplitude modulation scheme to reduce magnetic feedback between pickup and transducer. However, no controls are described or claimed.
U.S. Pat. No. 4,248,120 to Dickson, May 29, 1979, describes a stringed instrument sustainer, wherein the stringed instrument consists of a very long single string, of "30 to 100 feet in length". A sustain system is described for this device. The sustain signal is then mixed with the signal from an electric guitar in order to modify the sound of the guitar. No specific controls are described. The guitar which is described is not a physical part of the sustainer, nor are string vibrations of the guitar actually sustained by this invention.
None of the Coil/Core Magnetic Driver type sustainers described above is commercially available.
The "Infinite Guitar", invented by Michael Brook, is the first magnetic sustainer of the coil/core magnetic driver type for electric guitar known by this inventor to have received international attention. This sustainer was reported upon in a British publication Making Music, April, 1987. It was used on the Joshua Tree album by the rock music group U2, released in March, 1987. Apparently, no commercial success of this sustainer has been achieved, even though it has received limited press coverage and extensive public use by a world-famous musical group.
The "Infinite Guitar" sustainer (not shown) is designed to operate primarily with the Fender Stratocaster guitar. As shown in FIG. 2a, this model guitar has three pickups. They are normally of the single coil type. One of the pickups, typically neck pickup 212, is replaced with a "stack" type pickup. This "stack" type of pickup has two coils wound in opposite directions, connected in series, and stacked vertically such that only the top coil actually senses and responds significantly to string vibrations because of its proximity to the strings. Hence, the name. However, both coils do respond equally to external magnetic fields. Therefore, this configuration functions much like a "humbucker" pickup, where the two coils are placed side-by-side. Since the two coils are stacked vertically instead of being laid side-by-side horizontally, the "stack" humbucker takes up only half the area on the instrument body as the full-size humbucker pickup, and appears visually much like a single-coil pickup.
The "Infinite Guitar" sustainer uses this "stack" type neck pickup as the string driver transducer. This is because when used as a driver transducer, the radiated field of a "stack" pickup is less than with a single-coil transducer, because the same magnetic field cancellation properties of a humbucking pickup work equally well in the far field for a radiated magnetic field when the pickup is used in reverse as a driver transducer.
The controller, amplifier, and power supply are contained inside a metal box, which normally sits on the floor. There are foot-actuated switches which are used to turn the sustainer on and off, and also to reverse the phase in order to select the vibration mode of the strings. A shielded electrical cable routes the guitar pickup signal from instrument output jack 230 to the floorbox of the sustainer. Another shielded cable (not shown) then routes the transducer drive signal back to the instrument, where it is applied to the string driver transducer. The shielding isolates the pickup signal from the drive signal, because if not shielded, the capacitive interaction between the two signals would likely cause an uncontrolled oscillatory condition. No controls are mounted to the body of the instrument.
One problem with this sustainer is that there is no automatic pickup selection when the sustainer is turned on. In order to function best, the selected pickup should be the one farthest from the driver when the sustainer is on. This is because there is the least amount of magnetic crosstalk between driver and pickup, resulting in a minimum amount of noise and distortion introduced into the pickup by the transducer. This spacing also allows the highest possible system gain to be set in the sustainer for most robust sustainer performance. In the case of a Stratocaster guitar of FIG. 2a with a driver transducer (not shown) in the neck pickup position 212, the pickup farthest removed from this position is the bridge pickup 210. If, for instance, the pickup selector switch is set in the middle pickup position, less than optimal spacing is present. If the sustainer gain is optimized and adjusted for bridge pickup spacing, selecting the middle pickup with the sustainer on might even cause uncontrolled oscillation due to direct magnetic feedback between middle pickup 211 and transducer in neck pickup position 212. This would be a most undesirable situation in performance, because such an uncontrolled oscillation typically produces a loud squealing sound.
A second problem with the "Infinite Guitar" sustainer is the cable which connects the floorbox controller/amplifier with the transducer (not shown). This extra cable limits the musician's mobility when performing on stage.
U.S. Pat. No. 4,907,483 to Rose et al., Mar. 13, 1990, describes a sustainer of this type. The patent describes switches to turn the sustainer on and off, and also a potentiometer to control the phase of the drive signal to the transducer. No particular placement of the controls is specified or claimed. A prior art sustainer manufactured under the '483 patent by Kramer Music Products, Neptune, N.J., is a Kramer Floyd Rose Sustainer Solidbody Guitar. A review of that prior art was published in Guitar World magazine, 1989, July, page 106. Also, it is installed into certain Jackson guitars. Control of this sustainer consists of three toggle switches and a potentiometer, all of which are mounted into the body of the guitar. These controls are placed in addition to the "basic function" volume and tone controls of the guitar. This clutters the appearance of the instrument.
Another relevant prior art magnetic sustainer is provided by U.S. Pat. No. 4,941,388 to Hoover et al., Jul. 17, 1990, and also U.S. Pat. No. 5,050,759 to Hoover et al., Dec. 10, 1991. The Sustainiac model GA-1 and GA-2 sustainers, manufactured by Maniac Music, Inc. Indianapolis, Ind., are based on the '388 and '759 patents. These are sustainers which have achieved some commercial success. They were sold in certain guitars manufactured by Hamer Guitars of Chicago, Ill., during the time period 1989-1992. The GA-2 sustainer was sold in certain models of Fernandes guitars of Japan during 1990, 1991, and in guitars manufactured by Audio Sound International, a corporation of Indianapolis, Ind., during 1990, 1991. The GA-2 was also sold to individuals for retrofit into existing instruments during the same time period, and continues to be so at the present time.
These Sustainiac model GA-1 and GA-2 sustainers were designed to be wholly contained inside the body of typical electric guitars. The accessible controls consist of two toggle switches. A description of a typical installation of that sustainer in a common variety of electric guitar is described below, and shown in FIG. 5.
FIG. 5a contains a front plan view of the body 530 of a typical electric guitar 500. FIG. 5b contains a rear plan view, and FIG. 5c contains an electrical schematic of this same guitar. Guitar 500 contains three pickups for producing an electrical output signal in response to string vibrations. Bridge pickup 510 is a standard "humbucker" type of hum canceling pickup. Pickups 512 and 514 are typical single-coil pickups. Pickup selector switch S520 is a five position selector switch, similar to the pickup selector switch S270 of FIG. 2a. S520 can select the following five pickup combinations: pickup bridge pickup 510 only in switch position 520a (terminal 521 of S520), the combination of bridge pickup 510 and middle pickup 512 in switch position 520b (terminals 521 and 522 of S520), middle pickup 512 only in switch position 520c (terminal 522 of S520), the combination of middle pickup 512 and neck pickup 514 in switch position 520d (terminals 522 and 523 of S520), or neck pickup 514 only in switch position 520e (terminal 523 of S520). Volume control potentiometer VR534 and tone control potentiometer VR532 are provided to adjust the amplitude and frequency response, respectively, of the selected pickup signal at output terminal 538 of output jack J536. Knobs 534 and 532 are attached to the rotary shafts of potentiometers VR534 and VR532, respectively. The function of the rotary shafts is to move the potentiometer wiper elements, which move along the resistive elements of the potentiometer elements to select the desired tone and volume settings.
Referring again to the back plan view of body 530 of electric guitar 500: Cover plate 553a is shown, which covers cavity 553 (shown in hidden view) which is cut into body 530. The purpose of cavity 553 is to house electrical components VR532, VR534, and S520, plus the electrical wiring associated with them.
FIG. 5d contains another front plan view of the electric guitar body 500, which has been modified by the installation of sustainer 550 inside the body 530. FIG. 5e contains a rear plan view of the same instrument. Typically, the installation is done by cutting a cavity 551 into the back of the instrument in a convenient place, near the existing electronics cavity 553 which houses pickup selector switch S520, volume control VR534, and tone control VR532. Circuit board 550 containing the electronic circuitry of the GA-2 sustainer controller/amplifier is then placed in the cavity. Toggle switches S552 and S554 are permanently mounted to the circuit board. These toggle switches mount to the surface of the front of the body by threaded nuts, (not shown) and are the means by which the circuit board 550 is attached to body 530. Pickup selector switch S520 selects the same pickup configurations as in FIGS. 5a and 5d, as explained above. FIG. 5f contains a simplified schematic and functional block diagram of the sustainer, showing pertinent functional components and the relationship between the sustainer and the electronic components of a typical electric guitar.
The sustainer circuits are active but in standby mode whenever a standard 1/4 inch monaural phone plug is plugged into guitar output jack J536a. J536a is a standard 1/4 inch diameter stereo phone jack, which accepts a standard 1/4 inch phone plug. When a monaural 1/4 inch phono plug is inserted into J536a, ring terminal 537 is electrically connected to ground terminal 502. This connects terminal 537 to ground, which causes sufficient base current from darlington pair PNP transistor Q574 (shown as a single transistor for simplicity) to flow through R572 so as to place Q574 in saturation. The emitter of transistor Q574 is connected to dc voltage supply 558, which consists of two 9 volt batteries connected in series. The collector of Q574 is the dc power supply, Vcc, for all of the circuits in the sustainer. In standby mode, all circuits of the sustainer are powered. Input signal 535 from bridge pickup 510 is applied to the input terminal 539 of the sustainer. Bridge pickup 510 is chosen to provide the sustainer input signal because it is the pickup which is farthest from transducer 556. Operational amplifier U560 functions as a unity gain buffer amplifier for the input signal 535.
Toggle switch S554 is actuated to turn the sustainer ON and OFF. In FIGS. 5c and 5f, the up position of S554 indicated by arrow 590 turns the sustainer ON, and the down position of S554 indicated by arrow 591 turns the sustainer OFF. This switch has three poles. Pole S554C grounds out the non-inverting input of power amplifier U570 in the OFF position, which prevents signal from reaching the output of amplifier U570. The OFF position of pole S554B converts driver transducer 556 to a pickup, and to a string driver transducer when the S554B is in the ON position. In the OFF position, transducer 556 functions as a neck pickup instead of a string driver transducer, and produces a voltage in response to string vibrations at terminal 557. Terminal 557 of transducer 556 is connected to the intersection of two windings of voltage step-up transformer T580, terminals 581, 582. This transformer is connected as an autotransformer, with one end of the primary 583 being connected to ground. Output terminal 584 of transformer T580 is connected to terminal 523 of pickup selector switch S520. This corresponds to neck pickup select position 520d of S520 in FIG. 5e. With this connection of transducer 556 and transformer T560, the transducer 556 functions as a neck pickup when the sustainer is OFF and transducer terminal 557 is electrically disconnected from the power amplifier. Transformer T560 is used to increase the voltage output of the transducer in response to string vibrations. In many guitars which are modified with the installation of this sustainer, a neck pickup exists in the instrument. By using transformer T560 in conjunction with transducer 556 to form a pickup when the sustainer is off, no new cavity has to be milled into guitar body 530 in order to accommodate the transducer. This feature is explained is detail in U.S. Pat. No. 5,050,759 to Hoover et al., Dec. 10, 1991.
Pole S554A is used to select the bridge pickup 510 as the output signal of the guitar whenever S554A is in the ON position, regardless of the setting of S520, the pickup selector switch. This is done for two reasons: (1) the bridge pickup is the pickup on the instrument which lies physically furthest from the transducer, and therefore is least subject to magnetic crosstalk from the transducer. Therefore, bridge pickup 510 produces less audible crosstalk noise than middle pickup 512. Furthermore, bridge pickup 510 is a humbucking pickup, which is less susceptible to magnetic crosstalk from driver 556 than is a single-coil pickup. (2) because if pickup selector switch S520 is in the neck pickup position, the transducer 522 cannot be simultaneously a driver transducer and a neck pickup. In the OFF position of S554A, the instrument output jack is connected to the common terminal 524 of S520, such that pickup selection functions normally.
This selecting of bridge pickup 510 as the output signal of the guitar whenever S554A is in the ON position, regardless of the setting of S520, the pickup selector switch, is the primary reason why it has become a standard practice to install a magnetic sustainer inside of electric guitars instead of in a separate floorbox as in the case of the "Infinite Guitar".
Switch S552 is a three-position toggle switch, which switches the sustainer operation into three separate operational modes: Selection of switch terminal 552a selects fundamental mode, where string vibration is in the fundamental mode of vibration; switch terminal 552b selects mix mode, where string vibration occurs mostly in the fundamental mode of vibration for high frequency notes, and mostly in the harmonic mode of vibration for low frequency notes, as capacitor C563 resonates with the inductance of the coil of transducer 556; switch terminal 552c selects harmonic mode, where string vibration is in the harmonic mode of vibration.
In position 552a and 552b of switch 552, operational amplifier U568 functions as a unity-gain follower. The amplified signal which is applied to transducer 556 is in phase with the input signal from bridge pickup 510. In position 552c, the non-inverting amplifier input is grounded, which causes U568 to function as a unity-gain inverting amplifier.
The advantage of installing sustainer 550 inside the body 530 can be appreciated by examining the FIG. 5 drawings and by studying the above description. Clearly, when using the sustainer in the instrument shown, certain functionality of the instrument is decreased when the sustainer is in operation. This is because the magnetic field which is radiated by transducer 556 prevents the use of middle pickup 512 due to magnetic crosstalk. The neck pickup function is lost, because transducer 556 only functions as neck pickup when the sustainer is off. If original neck pickup 514 was placed directly adjacent to transducer 556, the problem of magnetic crosstalk would exist, and it could not be used when the sustainer was operating. These limitations would be present whether the sustainer was placed inside the body of the instrument or not, because they are a result of having a string driver transducer within close proximity to the neck and middle pickups. The advantage of automatic bridge pickup selection is obvious. It allows the musician to place the sustainer in operation without having to remember to select only the bridge pickup at the same time the sustainer is turned on. It would be very difficult to accomplish automatic pickup selection without placing the sustainer inside the body of the instrument. Separate shielded cables would have to be used to connect each pickup to an external automatic pickup selector circuit. If a sustainer of this type is to be used with a stringed instrument such as an electric guitar, it is obvious that it is advantageous to place it inside the body of the instrument.
The resulting disadvantage which is created is the same as that described in the previous paragraph for the Kramer Floyd Rose sustainer: Switches must be mounted to the body of the instrument, which clutters the appearance of the instrument. If the installation of the sustainer is a retrofit, then the instrument must be permanently altered in order to install the sustainer and switches. This reduces the value of the instrument.
Another example of a prior art magnetic sustainers is provided by U.S. Pat. No. 5,123,324 to Rose et al., Jun. 23, 1992. This sustainer describes controls which mount inside a box, which is mounted to the body of an instrument. No specific arrangement of controls is described or claimed.
U.S. Pat. No. 5,200,569 to Moore, Apr. 6, 1993, describes a sustainer having switches to turn the sustainer on and off, and to switch the phase of the drive signal. No particular placement of the controls is specified or claimed.
U.S. Pat. No. 5,233,123 to Rose et al, Aug. 3, 1993, describes another magnetic sustainer. This sustainer describes controls which mount inside a box, which is mounted to the body of an instrument. No specific arrangement of controls is described or claimed.
Other relevant prior art magnetic sustainers are provided by U.S. Pat. No. 5,292,999 to Tumura, Mar. 8, 1994, U.S. Pat. No. 5,378,850 to Tumura, Jan. 3, 1995, and U.S. Pat. No. 5,585,588 to Tumura, Dec. 17, 1996. None of these patents specify or claim any specific controls or arrangement of controls. Some of the described and claimed elements of the Tumura inventions can be found in the "Fernandes Sustainer", manufactured by Fernandes Guitars of Tokyo, Japan and distributed in the U.S. by Fernandes U.S.A. Controls for the Fernandes sustainer are identical to those of the Sustainiac GA-2. Therefore, the same problems exist.
U.S. Pat. No. 5,449,858 to Menning et al, Sep. 12, 1995, describes a multipurpose feedback device which has all of the elements of a magnetic sustainer. The device magnetic transducer is described as being held in or attached to the hand or other parts of the musician's body. No specific controls or special arrangement of controls are described or claimed, although a "signal processor" box is described as having control capabilities.
Still other examples are shown in U.S. Pat. No. 5,523,526 to Shattil, Jun. 4, 1996. The Shattil patent neither specifies nor claims any particular controls or arrangement of controls.
Neither the Menning nor Shattil sustainers has been commercially available, as far as this inventor knows.
Of all the coil/core magnetic driver sustainers mentioned above, only the following examples are known to this inventor to have achieved any degree of commercial success: The "Floyd Rose" sustainer, "Sustainiac GA-1" sustainer, "Sustainiac GA-2" sustainer, and "Fernandes" sustainer. These examples are similar in that they are all totally contained within the body of electric guitars, and are powered by batteries. However, examination of retail store displays, advertisements, public guitar shows and conventions around the U.S. reveals that when compared to other types of effectors, sales volume of these sustainers is not large. This inventor believes that the fact that the controls of these sustainers are discernible on electric guitars, and cause them to appear different from guitars which are not equipped with sustainers.
(A-2) Conducting String Magnetic Driver
Another type of magnetic sustainer has basic sustainer elements (1)-(4) as described above, but with a different magnetic string driver configuration: The magnetic string driver (5) function is accomplished in the following manner: The amplifier output feeds alternating current in response to string vibrations into the strings, which act as electrical conductors. The alternating magnetic field which surrounds each string due to the current flowing through it interacts with a permanent magnet which is mounted onto the instrument body underneath the strings. Thus, electrical energy coming from the amplifier is converted into magnetic energy, and finally to vibrational energy in the strings.
U.S. Pat. No. 4,137,811 to Kakehashi describes a prior art sustainer of this type. No commercial example of this sustainer is known to this inventor. No specific control arrangement is specified in the patent. In the U.S. Pat. No. 5,378,850 Tumura patent, two Japanese patents are described, 52-151022 and 53-139836, both owned by Roland Corporation, which disclose this type of sustainer. This inventor does not have access to these prior art patents. Since the '811 Kakehashi patent is assigned to the Roland Corporation, these could be similar.
An example of this prior art sustainer is provided by U.S. Pat. No. 4,181,058 to Suenaga, Jan. 1, 1980. No commercial example of this sustainer is known to this inventor. Controls consisting of numerous switches are described and illustrated in drawings. These controls are shown mounted to the surface of the body of a guitar. The problem with this type of control system is that numerous switches are mounted to the body of the instrument, which clutters the appearance. If the sustainer is used as a retrofit item, then the end user would have to modify the body of the instrument in order to mount the switches. This would likely decrease the value of the instrument.
(A-3) Hand-Held Sustainer
This type of magnetic sustainer has all basic sustainer elements (1)-(5) contained inside a small box which is held in one hand of the musician. The sustainer is used by holding it along the length of a single string of an instrument having steel strings. This example is described in U.S. Pat. No. 4,075,921 to Heet, Feb. 28, 1978. A sustainer having the trade name of "E-Bow" is available in the marketplace. The control of this sustainer consists of a single on/off switch, which is located on the sustainer enclosure. In this case, the sustainer must be stored in some convenient position until the musician is ready to use it. After reaching for and grasping the E-bow sustainer, the musician must actuate the power switch. An alternative method of activating the sustainer would be to first switch the sustainer on before starting a song. Then, sometime during the song when the sustainer is needed, it can then be quickly grasped and used. The E-Bow sustainer has achieved some limited commercial success. The E-bow obviously presents considerable problems to the musician who wishes to switch back and forth quickly between normal playing style and sustained notes.
All of the sustainers described in (A-1), (A-2), and (A-3) above are of the electromagnetic-type sustainers.
(B) Descriptions of Electroacoustic Sustainers Follow
(B-1) One type of electroacoustic sustainer string driver first converts the amplified alternating electric signal coming from the amplifier into a pulsating magnetic field. Then, due to the mechanical construction of the transducer, the pulsating magnetic field is converted into a pulsating acoustic vibration, which is applied directly to some part of the body of the instrument. The acoustic vibrational energy then travels through the body to one or both ends of the strings, and is transferred to them. This then restores vibrational energy which would normally be lost due to normal frictional losses in the strings, and thereby sustains the string vibration.
Several examples of this type sustainer exist. The first known to this inventor is disclosed in U.S. Pat. No. 2,672,781 to Miessner, Mar. 23, 1954. This sustainer comprises vibrating reeds mounted to a reed plate. Pickups convert reed vibrations to electrical signals. An amplifier applies amplified pickup signal to a driver transducer. The driver transducer mounts to the reed plate which is vibrated by the transducer. This sets up sustained vibration of the reeds. A potentiometer is described which controls reed vibration amplitude. No details of mounting of this control are given.
U.S. Pat. No. 3,571,480 to Tichenor et al describes a feedback loop for musical instruments which contains all of the elements of this type of electroacoustic sustainer. No controls are described or claimed.
U.S. Pat. No. 3,813,473 to Terymenko, May 28, 1974, describes an acoustic sustainer where an electromagnetic string driver transducer having a single coil is attached to the bridge of a guitar. The string vibrations are sustained as one end of the strings are imparted vibrational energy by the transducer through the vibrating bridge. Numerous controls are described which are actuated by footpedal, and are located in a floorbox. The driver transducer in the Terymenko patent is alsospecified as being capable of exciting the strings into sustained vibration through direct magnetic energy transfer.
U.S. Pat. No. 4,236,433 to Holland, Dec. 2, 1980, describes an acoustic sustainer for an electric stringed instrument. Individual sustainers are provided for each string. All pickups and transducers are mounted to a special bridge assembly. The bridge assembly anchors one end of each of the strings. Amplifiers and control potentiometers are mounted inside a box which sits on the bridge assembly near the ends of the strings. The potentiometers control the gain of the amplifiers.
U.S. Pat. No. 4,484,508 to Nourney, 1984, describes an acoustic sustainer for an electric stringed instrument. Amplifier and control circuitry are described as being external to the instrument. Various controls are described and depicted as also being external to the instrument. The patent describes no embellishment or arrangement of controls whereby switches are an integral part of any control potentiometer on the instrument, such that the original appearance of an instrument is substantially preserved after being modified by the addition of the sustainer.
U.S. Pat. No. 4,697,491 to Maloney, Oct. 6, 1987, describes an acoustic sustainer for an electric stringed instrument. The transducer mounts to the headstock of the instrument. The amplifier is described as being mounted inside a floorbox, with a phase reversal switch also being included inside the box.
No commercial examples of the electroacoustic sustainers described above are known to this inventor.
Another prior art acoustic sustainer is disclosed in U.S. Pat. No. 4,852,444 to Hoover et al., Aug. 1, 1989. That prior art provides an electromagnetic transducer affixed to a musical-instrument body. The "Sustainiac Model T" and "Sustainiac Model B" sustainers are two examples of sustainers which are based on this patent. Amplifier and controls for these sustainers are located in a floorbox. Some commercial success of these sustainers has been achieved. The "Sustainiac Model B" sustainer continues to sell at the present time. One disadvantage of this particular sustainer is that an electrical cable must be used to connect the transducer, which is mounted to the headstock or some other part of the body of an electric guitar or other electric stringed musical instrument, to the floorbox. This can create a problem when playing onstage, because the cord can impair motion, particularly for musicians who tend to move around the stage a lot when performing. As a result, this device tends to sell more to studio musicians, where dancing or other large movements are less likely to be made while playing.
An acoustic sustainer such as the "Sustainiac Model B" can be placed entirely inside the body of the instrument. This solves the problem of having an extra cable to deal with. Since the transducer of the "Sustainiac Model B" sustainer is usually mounted to the headstock of an electric guitar, magnetic feedback between transducer and pickups is usually not a problem, due to the relatively wide spacing between the headstock of a guitar and the pickup location on a typical guitar body. Therefore, no automatic pickup selection is needed when the sustainer is turned on.
However, in some cases it might be desirable to place the transducer of the "Sustainiac Model B" in such a way that instead of vibrating a guitar headstock, instead it vibrates the guitar bridge. This would place the transducer much closer to the pickups. In this situation, having automatic pickup selection to a pickup farthest removed from the transducer would be a definite advantage, much as it is for a magnetic sustainer such as the Sustainiac GA-2 sustainer.
Another prior art acoustic sustainer is disclosed in U.S. Pat. No. 5,031,501 to Ashworth, Jul. 16, 1991. The patent describes and claims means for attaching an audio transducer to a stringed musical instrument. No controls are specified or claimed. Ashworth U.S. Pat. No. 3,449,531 is the transducer described in '501, but is not specifically a sustainer. No commercial example of a sustainer using this technology is known to this inventor.
U.S. Pat. No. 5,054,361 to Usa, Oct. 8, 1991, describes an invention which vibrates the body of a musical instrument in response to notes played on the instrument for the purpose of producing tactile vibratile sensations in the hands of the musician is disclosed. The drawings clearly depict a piano. This invention is not a sustainer. Switches are described which appear to be hidden by and are actuated by the keys of the piano, although they are not specified or claimed to be hidden. U.S. Pat. No. 5,189,242 to Usa, Feb. 23, 1993, describes the same electronic musical instrument as the '361 patent. In this patent, the hidden actuator switches are claimed.
U.S. Pat. No. 5,275,586 to Oba et al, Nov. 16, 1993, describes an invention which vibrates the soundboard of a musical instrument with a transducer in response to notes played on the instrument for the purpose of modifying the sound of the notes played on the instrument. No sustain device is specifically described or claimed. Switches and other controls are described as being mounted onto a control panel. No commercial example of a sustainer using this technology is known to this inventor.
No commercial electroacoustic sustainers of this type are known by this inventor to be designed to be totally mounted inside of a stringed instrument such as a guitar. However, there could be advantages similar to those of magnetic sustainers of the coil/core driver type. If the transducer of an acoustic sustainer was used to vibrate the bridge of an electric guitar, then the transducer might be mounted in close proximity to the bridge pickup, and further away from other pickups on the instrument body. Then, automatic switching away from the bridge pickup to one of the other pickups would be a distinct advantage. But, mounting the sustainer inside of the instrument would cause the necessity of mounting other controls of the sustainer on the instrument body. This would result in a cluttered appearance of the instrument, unless steps were taken to mount the added controls in such a manner as pot to detract from a desired appearance of the instrument.
(B-2) Another type of electroacoustic sustainer string driver utilizes a common cone-type electromagnetic loudspeaker mounted to the body of a stringed instrument, in close proximity to the strings. The vibrating air molecules emanating from the speaker impinge upon the vibrating strings of the instrument, which restores vibrational energy to the strings that would normally be lost due to normal frictional losses, and thereby sustains the string vibration. Typically, these airborne vibrations impinge upon the strings at a location other than the ends. Alternatively, vibrations in the frame of the loudspeaker can transmit vibrations into the body of the instrument, which are then coupled into the ends of the strings after traveling through the instrument body.
The first sustainer of this type known to this inventor is U.S. Pat. No. 1,893,895 to Hammond, Jun. 13, 1929. This patent is primarily one describing a sound reinforcement means for a piano or other musical instrument, having pickups, control means, amplifier, and loudspeaker. The patent describes the loudspeaker as being mounted to the sounding board of the instrument, and having the capability of reducing the string vibration damping by coupling vibrational energy from the loudspeaker to the strings through the air and also through the sounding board. Multiple potentiometers are described which are used to control the amplitude of the pickup signals to the amplifier. No special mounting or positioning of the controls is mentioned in the patent. No commercial example of a sustainer using this technology is known to this inventor.
Another patent by Hammond, U.S. Pat. No. 2,001,723, Jun. 16, 1932, describes a "regenerative piano". It also describes an instrument having, having pickups, control means, amplifier, and loudspeaker. It includes a filter network to minimize spurious oscillation occurring due to sounding board and pickup natural vibration frequencies. By minimizing spurious oscillations, sustain of note vibrations is prolonged. Potentiometers are described which set the gain of different string groups, in order to equalize sustain of all strings on the instrument. U.S. Pat. No. 3,612,741 to Marshall, Oct. 12, 1971, describes a sustain device substantially similar to the U.S. Pat. No. 2,001,723 device. No controls are described or claimed. No commercial example of a sustainer using this technology is known to this inventor.
A prior art acoustic sustainer is disclosed in U.S. Pat. No. 4,245,540 to Groupp, Jan. 20, 1981. That prior art provides a musical instrument having a loudspeaker mounted to the body of a guitar, located underneath the strings, an amplifier to drive the loudspeaker with the amplified pickup signal of the guitar. Because the loudspeaker is located within close proximity to the strings, string vibrations are sustained by imparting vibrational energy from the loudspeaker to the strings through the air. A control panel is mounted to the surface of the instrument which has all of the controls necessary to operate the sustainer. No effort is made to incorporate the sustainer controls and the normal function controls of the guitar so as to hide the additional controls required to operate the sustainer. Therefore, the appearance of the guitar body appears cluttered and unlike that which has gained popular acceptance. No commercial example of a sustainer using this technology is known to this inventor.